I really wouldn't mind buying special purpose hardware. In fact, I think I prefer it.
The whole story here is that modern SSD controllers tend to embed a bunch of very fast very expensive data-processing cores to quickly do a ton of fancy mapping. We don't hear it quite as clearly these days, but for example for a while higher end Samsung SSD controllers were announced as penta-core ARM Cortex-R[1] systems, and I think those Cortex-Rs are what most folks do. (It was groundbreaking news that WD released an open source "swerv" RISC-V core which they'd experimented with using instead, https://blog.westerndigital.com/risc-v-swerv-core-open-sourc... .)
Ideally, the fantasy is, we can build much cheaper & faster controllers that do far less. Zoned Namespace drives should ideally have enterprise grade, fast, dual-port access, but in many ways, I feel like they should ideally be far cheaper than DRAM-less drives. They should leave even more up to the host. They should be incredibly dumb & simple drives. They should be lower power, by far. They should eskew DRAM. Drop all the legacy baggage & expose what you are, un-intermediated, so we can be fast & use it well. Which you, the drive, with all purpose tasks, could never do.
It's not worth it, to me, to make a drive that still keeps the ancillary old baggage of convention. If you want to make a good ZNS drive, make a good ZNS drive.
[1] https://en.wikipedia.org/wiki/ARM_Cortex-R